Dr. Daniel Krowchuk, a pediatric dermatology specialist at Wake Forest Baptist Health Brenner Children's Hospital, presents case studies of children with birthmarks, melanoma and rashes, and describes how these occurrences may be symptoms of more serious conditions.
Part 3 of 3
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View Doctor Profile DANIEL KROWCHUK: OK. So this is an eight-year-old who I saw a number of years ago who has a recurring rash on the backs of his thighs. The funny history is it's present during the fall, but not during the summer or winter. And I think what you can see there are two little patches on the posterior thighs that look sort of eczematous, right? They're a bit red; they're a bit rough. So the first question-- is this an exogenous process or an endogenous process, right? So is this an outside job or an inside job? What do you think? SPEAKER: Outside. DANIEL KROWCHUK: Sure, it's an outside job. I mean, what self-respecting systemic illness is going to give you a rash with just two little areas of involvement on the posterior thighs, right? So then-- and this is why medicine is so much fun-- you have to be a bit of a detective. And it helps if you know that the chairs in schools are often constructed such as the one on the left, and they have bolts containing nickel that affix the legs to the seat of the chair. And so you can see why the location on the posterior thighs-- and if I can do this-- so now can we explain the history? [CHATTER] Yeah. So shorts during the fall, right? Long pants during the winter, although nowadays, it's not very fashionable to do that. And he's not in school in the summer, right? OK. So this is called the school chair sign. I put the reference there for you if you want to look it up. And on the upper-right photograph is a more recent report of this. And the thing that's so unusual about it is you can see that on her posterior thigh on the left, the lesion is in the correct spot, but the one on the right is much more proximal. So the folks who wrote this up were very clever. They went back and looked at the history again. And it turns out her way of sitting in her chair at school-- I would do this, but you wouldn't be able to see it-- is kind of slouched over, laid back with one leg across the other, so that explains the asymmetrical location of her lesions. [LAUGHTER] OK, so I want to take this moment to digress a bit about some standard forms of contact dermatitis and some newer forms. So poison ivy is something that we'll be seeing again not-too-distant future. So in its classic form, you see the photograph in the lower left, where at least in some areas, you have a linear distribution of lesions, and in this case, vesicles, right? So you can envision that the individual rubs up against a poison ivy plant, damages the plant, and in a linear distribution, the resin is applied. And because this is a very potent antigen, you get what's called an acute dermatitis. So you get lots of erythema, and you get vesicles. And that's well and good. That's an easy diagnosis. The problem is that that isn't the most common presentation. So let's say I'm out in the yard, and I'm working, and I've managed to get poison ivy resin on my T-shirt. It's a hot day, so I stop to wipe away the sweat. So I don't get a linear application of the resin, and I don't get as concentrated an application. So if you look at that upper-right photograph, I'd encourage you to burn that into your memory. So those very, very fine papules on a background of erythema is absolutely classic for contact dermatitis due to plant. And you may see those patches in a scattered distribution on your patient's skin. OK, so we talked about one form of nickel. So I'm not the sharpest knife in the drawer, but if my patient shows me the lower-left photograph, a chronic dermatitis picture next to a clothing snap, I'm hoping I'm going to make that connection. [LAUGHTER] So nickel is not as potent an antigen as poison ivy, so it doesn't give you acute dermatitis. It gives you a chronic dermatitis that looks like sort of chronic eczema. And nickel's in a lot of things. So you've seen an example of a clothing snap there. The right-hand photograph was a belt buckle that was the culprit. You can have the lobule of the ear, the side of the neck in the upper-right photograph from a necklace, and even eyeglass frames, as you see in the lower-right photograph. Now, I want to talk about some newer forms of contact dermatitis that have emerged in the literature over the past few years. So the girl on the left was using wet wipes to cleanse her face. And while in most cases that's perfectly fine, there are preservatives used in some forms, and that preservative ended up being the culprit for her perioral rash. And when the wet wipes were removed and an appropriate topical corticosteroid used, she got better. So as you're thinking about contact dermatitis, some of this is thinking about the location and what's plausible and also a careful review of products that they might be using on the skin. And many times, this can be difficult to sort out, and you may need your dermatologic colleagues to do patch-testing to figure out what the exact culprit is so that it can be avoided. On the right is an interesting one. This is a car seat dermatitis. And you can see sort of patches of erythema and rough skin on the lateral leg and the elbow. Now, there's a bit of controversy about whether this is a true allergic contact dermatitis or more of an irritant process. But again, it's thinking about the location of the eruption and what is coming in contact with the skin. Toilet seat dermatitis can occur. In times past, this was often due to varnishes on wooden toilet seats. I'm not sure why anybody ever thought a wooden toilet seat was a good idea. [LAUGHTER] But in more recent years, it turns out that polyurethane used in the plastic toilet seats can be a culprit. Again, the pattern of that eruption should give you some sense that something in contact with the bottom is the problem. On the right-hand photograph, shin guards contain a variety of irritant things as well as products that can induce an allergic response. Again, the location is going to help you. And I've summarized some of these newer forms of contact dermatitis in this table for you. The ones that I didn't show you photographs of were the preauricular area, or lateral neck. It turns out that nickel or chromium in some cell phones can induce that. And then the breast, so there is formaldehyde in some foam-containing bras. And lastly, under-wire bras often contain nickel that can induce a contact dermatitis. So again, location, location, location. All right. Zero response to treatment. So this is a four-year-old boy who developed a round spot in his popliteal fossa. Just one, one-sided, unilateral. His physician diagnosed him as having eczema, and he was treated with hyrdrocortisone 2.5% and later with mometasone ointment, because he didn't respond to the hydrocortisone. And remember that mometasone, with an ointment vehicle, turns out to be a fairly potent topical corticosteroid. So despite this, the rash spread, and the remainder of his examination is normal, so we need to think about the diagnosis. Well, the commonest round things that we deal with are nummular eczema. So as you see on the left, there's a patch. There's crust present, not really scale, and the border isn't elevated, as contrasted with tinea corporis on the right, where the border is more erythematous. It's elevated, and there is scale. So let's think through this problem. So he's got this round lesion that didn't respond to a topical corticosteroid. So that would make something eczematous unlikely, right? Or you'd at least think so. And the message that I would have you take away from this is if you're treating what you think to be ezcema with a topical corticosteroid, and it's not getting better, think fungus. So this child had some scale. It's a little bit subtle. And I think you'll notice that there are lots of erythematous papules and some pustules. And it turns out, when you treat tinea corporis with a topical corticosteroid, it sort of alters the appearance of the lesion. It drives the fungus deep into the follicle, so you end up getting this folliculitis with papules and pustules, and you may still get some scale. But the appearance is clearly very different than what you would anticipate from tinea corporis. So we did a KOH preparation that was positive. We did a culture as well that was positive and ended up treating him with oral griseofulvin. And just a couple of examples of this. So when you change the appearance, the dermatologists use this term, tinea incognito, because the appearance has changed. And these granulomas are termed majocchi granulomas, and they create these papules and pustules. And these are just two more examples. On the left, you can see sort of a ring, but not typical of tinea corporis. And the other thing that happens if you use steroids on something fungal is you often get this appearance of rings within rings, as you see on the right-hand photograph. OK. So I'm going to conclude. We're coming into warm-weather months, so I have just two bits of advice. To make our Zika connection, this is the results of a study that I'll go into in a little bit of depth that appeared in a journal that I know you all read, the Journal of Insect Science. [LAUGHTER] And it was picked up by National Public Radio and broadcast early in February. And they're the folks who created this graphic. So what they looked at is how well various insect repellents worked. And their way of doing this is they put the insect repellent on the extremity of a volunteer and then looked at how attracted mosquitoes were to that extremity. So low numbers-- this is like golf-- low numbers are good. So this may be difficult to see, depending on how far you are from a screen. But if you look at the low numbers, those are all DEET-containing products, with a couple of exceptions. There's a Cutter lemon eucalyptus insect repellent that worked well. In the left-hand column is immediate efficacy. The right-hand column is after four hours. So as a rule, DEET-containing products give you the best efficacy and the longest duration. Now, the problem is, as I put in a footnote on the left-hand side of this slide, they did not test a very effective agent called picaridin, which is present in many insect repellents. So picaridin turns out to be just as effective as DEET at comparable concentrations. Now, I think all of us have heard about Avon's Skin So Soft as something that is very effective at repelling mosquitoes. And as you can see from this, that's not the case. Now, interestingly, they also tested a couple of fragrances, which I thought was kind of humorous, including Victoria's Secret Bombshell. [LAUGHTER] And as it turns out, that is a very good insect repellent. It does make me wonder its effect on humans, but that's another matter entirely. Now, some of you who know me know that I'm a little bit fussy about spelling and grammar, so it's nice to know that sometimes journalists make mistakes. Because mosquitoes, like tomatoes or potatoes, are spelled with O-E-S. But it's not so bad, because as I recall, there's a former president who got tripped up on this as well. [LAUGHTER] OK, so a word more about DEET. So if you look at bullet two on the left column, as it turns out, DEET, its efficacy plateaus at about 30% concentration. And increasing the DEET concentration actually increases the duration of effect more so than its efficacy. So if you choose a 10% product, for example, that's going to give you a couple of hours' protection, which is great for the backyard. But if you're out camping, you might want to bump that, because if you go to 30%, for example, or 25%, you'll get five hours of protection. The authors of that previous study also said-- sort of reinforced what Dr. Abramson said-- about using protective clothing. So thick, long sleeves, long pants. Now, the exception to that, interestingly, in their article, was Spandex. They said that mosquitoes can actually bite between the fibers in Spandex. And that doesn't bother me, because nobody wants to see an old guy in Spandex. So you will never see me using Spandex. They also said it's a good idea to cover your feet, so sandals are not good. If you didn't already know that mosquitoes are disgusting creatures, they seem to have a predilection and a fondness for the aroma of feet, so they are going to go for your feet. All right. Lastly, just a word about sunscreens, as we start using these things. And I just wanted to review. Remember that UVB protection is kind of something that is reflected by the SPF factor. UVA protection, as of a couple of years ago, is now one star to four stars, four stars being best. So you want to choose a product ideally that has both UVA and UVB protection-- UVA because, not only is it important in aging, but it does seem to have some role in skin cancer. And then I would just draw your attention to the third sub-bullet in the left-hand column. So as it turns out, in order to get optimal SPF factor, you have to apply 2 milligrams per centimeter squared or, for an average adult, 1 full ounce of product to cover your entire body one time, which, as it turns out, nobody does. So people typically apply 1/4 to 1/2 the recommended amount, which reduces the effective SPF by the 1/4 or square root, respectively. So if you started out with an SPF 16 sunscreen, and you put on 1/4-- so the square root of that is 4, and the square root of that is 2, so now you're at SPF 2. So I suggest to families, choose a product that's got a high SPF. If you used it in an ideal way, that would be unnecessary, but it does give you a little margin for error.